Transformer



April 15, 1924.

. W. S. MOODY TRANSFORMER Filed April 15. 1922 I I I I I 411.111, I. r

. Ihventor WaltePSMoody,

His Attorney Patented Apr. 15, 192 4.

UNITED STATES PATENT OFFICE.

WALTERS. MOODY, 0F PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, A CORPOR! PICK OF NEW YORK.

TRANSFORMER.

Application filed April 15, 1922. Serial No. 553,259.

To all whom it may concem:

Be it known that I, WALTER S. MOODY, a citizen of the United States, residing at Pittsfield. county of Berkshire, State of Massachusetts, have invented certain new and useful Improvements in Transformers, of which the following is a specification.

My invention relates to transformers and its general object is to provide an improved construction for limiting the current delivered by a transformer to safe maximum values.

Excessive current accompanied by overheating and injury may occur in a transformer winding if it is connected to supply too many circuits at one time or if a. fault such as a ground or a short circuit occurs in one of the circuits. Such troubles are avoided in accordance with this invention by the automatic insertion of reactance whenever the current reaches a predetermined maximum value, the reactance-serving to reduce the current until such timeas the abnormal circuit conditions are removed. A further object of the invention is to provide a construction so arranged that upon removal of a fault or other abnormal condition causing an overload on a transformer,

the protective reactance will be automatically removed. and normal operating conditions restored. The invention may be used to advantage in connection-with a variety of different types of transformer and transformer connections but is particularly applicable in protecting transformers supplying current for signalling devices such as electric bells and buzzers and its objects and advantages will be described in this con nection.

One embodiment of the invention is illustrated in the accompanying drawing in which Fig. 1 is a perspective view of a transformer construction embodying the invention and Fig. 2 is a diagrammatic view of the transformer shown in Fig. 1, the transformer being connected to supply current to 3 number of bell ringing circuits.

Like reference characters refer to similar parts in both figures of the drawing.

In the particular embodiment of the invention shown in the drawing, a transformer 1 includes a core 2 with its winding legs surrounded by primary windings 3 and secondary windings 4. A member 5 of ma netic material, carrying an auxiliary win ing 6 and surrounded thereby, is arranged to move toward and from a portion of the core 2, the means shown for guiding it in these movements being non-magnetic pins 7 fixed to the member 5 and sliding freely in holes 8 in the core. The movements of the member 5 vary the lengths of the air gaps between its end portions and the cor 2, thus varying the reluctance of the magnetic circuit comprising these air gaps, the member 5 and the core 2. The ends of the member 5 project toward the core to close the air gaps when this member is nearest the core. The winding 6 is connected in series with the secondary windings 4 to a dis tributing circuit 9 which feeds individual circuits each leading to a signal device or hell 10 controlled by a push button 11. The primary windings are connected across a supply circuit 12 which may be some convenient power or lighting circuit.

The ends of the magnetic member 5 are normally spaced from the core 2, being held so by gravity or otherwise. When current is taken from the transformer through the winding 6 under these conditions, the reactance of this winding 6 is not great because of the high magnetic reluctance of the air gaps between the memberv 5 and the core 2. The arrangement is such, however, that when the current taken from the transformer exceeds a safe maximum value, due

to a short circuit, ground or other abnormal condition, the magnetic flux induced bythe winding 6 in the member 5 and core 2 is suflic'ient to draw the member 5 toward thecore 2 to reduce or close the air aps. This results in a greatly decreased re uctance in the magnetic circuit through the member 5 and core 2 and a correspondin large increase in the reactive effect of t e winding '6. The reactance thus automatically introtect the transformer windings and load circuits and apparatus until the removal of the abnormal conditions. As soon as these conditions are removed and the current is sufiiciently reduced, the member 5 is returned to its normal position by gravity or otherwise, the weakened magnetic flux being no longer capable of holding the air gaps closed. While the member 5 is shown as being movable toward and from the core .tively related to the auxiliary winding, said magnetic member and auxiliary winding being movable under the influence of current in the auxiliary winding to vary the reactance of the auxiliary winding.

2. A transformer including a core with primary and secondary windings, an auxiliary winding in series with the secondary winding, and a magnetic member induc tively related to the auxiliary winding, said magnetic member being movable toward and from said core under the influence of current in the auxiliary winding to vary the reactance of the auxiliary winding.

3. A transformer including a core with primary and secondary windings, an auxiliary winding in series with one of said core windings, and a magnetic member inductively related to the auxiliary winding, said magnetic member being movable under the influence of current in the auxiliary winding to vary the reactance of the auxiliary winding. a v

f A transformer including a core with primary and secondary windings, an auxiliary winding, and a magnetic member 1nductively related to the auxiliary windin said magnetic member and auxiliary win ing being arranged to be moved from normal position under the influence of current of one value in the auxiliary winding to increase the reactance of said auxiliary winding and to return to normal position when the current has been reduced to some lesser value. i

In witness whereof, I have hereunto set my hand-this 13th day of April, 1922.

WALTER S. MOODY. 

